damn you're gonna get flamed......
first off, using a gsr block = vtec block would not be considered LS/VTEC. You may wanna goodle what ls/vtec is. Ls/vtec is made by using a non vtec block i.e. b20/b18a/b with a vtec head i.e. pr3 or p72. Also LS rods are weak, they will not be able to support high revs. One last note, LS rods wouldn't even fit in a b18c block. There are tons of threads on this subject, do a little search and you will find your answers. Matter of fact, is a link to your answers ON TOP OF THIS THREAD.
How to build a "RELIABLE" lsvtec/b20vtec guide.